There have conventionally been used foamed moldings such as soft polyurethane foamed moldings for interior parts example of which include a seat and a door of a vehicle such as an automobile or an electric train. In a manufacturing process of the foamed moldings, a certain amount of foam resin material for forming the soft polyurethane foam is supplied in the forming mold, first. Then, the forming mold is closed, and the foam resin material is foamed and cured. The foam resin material is gradually filled in a cavity while expanding, and forms into a shape corresponding to the cavity. In this process, if a gas such as carbon dioxide generated by air existing inside the mold or by a foaming reaction is not properly exhausted outside the mold, defects such as an underfill or a void can be formed in the molding.
Therefore, there is a known concept of providing a vent hole in the forming mold to exhaust the gas inside the mold. However, simply providing the vent hole may exhaust the foam resin material filled in the cavity outside the mold through the vent hole, thereby causing problems such as material loss and necessary cleaning of the vent hole.
As shown in FIGS. 4 and 5, as a mold 30 configured to prevent a material from being exhausted from a vent hole, Japanese Unexamined Patent Application Publication No. 2006-192831 discloses a configuration where the inside of a forming mold is provided with a plate-like slab having air permeability on which a non-air-permeability sheet 32 capable of covering a vent hole 31 is adhered, or provided with a nonwoven cloth 33. With this mold 30, gas flows out through the vent hole 31 via the slab or the nonwoven cloth 33, in the foaming process. When the inside of the cavity 34 is filled with resin 35, the foaming pressure of the foam resin material causes the non-air-permeability sheet 32 to press against the vent hole 31 to close the vent hole 31. As a result, the resin is prevented from entering the vent hole 31.    Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2006-192831